FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY IN THE CHARACTERIZATION OF SOME ENANTIOMERICALLY PURE FLUORINATED BETA-PHENYLSERINES

The fast atom bombardment-induced mass spectrometric behaviour of six enantiomerically pure and fluoro-substituted beta-phenylserines was st udied in detail with the aid of metastable ion data. Results show main ly that the formation of the imminium cations, a decomposition pathway characteristic of non-fluorinated analogs, is strongly reduced, while water loss becomes the preferred primary decomposition route. Fluorin e-containing substituents are also active in promoting the formation o f polycyclic product ions which allow the characterization of the vari ous isomers to be performed.